Poly(tetramethylene ether) glycol (PTMEG) is a commodity in the chemical industry, widely used in the manufacture of polyurethanes and polyesters. It is commonly prepared by reacting tetrahydrofuran (THF) with fluorosulfonic acid and then quenching the product with water. While this process has proved to be quite satisfactory, it is not as efficient as desired because the acid cannot be recovered and reused. Moreover, disposal of the spent acid is a problem because of its toxicity and corrosiveness.